The building materials or ceiling tiles are used in the building trades to provide original ceiling structures or replacement covering ceiling structures. The ceiling tiles may be directly mounted to a building surface or they may be mounted in a suspended ceiling arrangement using a grid support fixed to the building structure. The tiles are prepared from a slurry of fibers, fillers and binders.
Of particular interest herein, the tiles are prepared using compositions and cast procedures such as those disclosed in U.S. Pat. Nos. 5,395,438 and 1,769,519. According to these patent teachings, a molding composition comprising fibers, fillers, colorants and a binder, in particular a starch gel, is prepared for molding or casting the body of the tile. This mixture or composition is placed upon suitable trays and then the composition is screeded to a desired thickness with a screed bar or roller. The trays filled with the composition are then placed in an oven to dry or cure the composition. The dried sheets are removed from the trays and may be treated on one or both faces to provide smooth surfaces, to obtain the desired thickness and to prevent warping. The sheets are then cut into tiles of a desired size.
Chitosan or poly-D-glucosamine is commercially available as a deacetylated form of chitin which is a structural element in the exoskeleton of crustaceans and the cell walls of certain fungi. It is a cationic polymer similar to cellulose. Chitosan has been found to promote blood clotting and it has been used in bandages. It is a biocide and has special properties that enhance antimicrobial and antifungal activities. Chitosan is also used as a flocculent in the water filtration of heavy metals. Chitosan is also indicated to absorb formaldehyde and odor.